Cranked engine and engine swaps

[Rebuilder]

Cracked engine and engine swaps

Hey guys. New guy here looking at a few LMTV's to buy and one says it has a cracked engine block at only 2000 miles. No other details. Is there a common place where the Cat 3116 crack or is it possible it was filled with water instead of coolant and cracked when it froze? I doubt it's the latter but I know it has happened when California cars get moved north. Also, has anyone done an engine swap in one of these? 3116 seem to be good engines but would something like a 6BT Cummins work? I know those are built for smaller trucks but they're around the same HP as the 3116 and there are tons of HP upgrades available.

Thanks
Terry

 

[mkcoen]

PS Magazine had an article about drive shaft maintenance that talked specifically about cracking the block due to too much play in the drive shaft. Not saying that's what caused this one but it is a known issue. I would think trying to get the 6BT fabbed into a LMTV would be a whole lot more nightmare than finding a good take out 3116.

 

[scottmandu]

The bell housing has been known to crack mainly due to drive shaft problems. But the 3116's don't have a place they crack that is inherit to the engine. You could put in any other engine with a #2 SAE bell housing. Although not impossible it would be a challenge with the cooling fan mounted to the crankshaft, and engine mounts, flywheel etc. If your looking for a repower I'd look at the Cat C7 or possibly C9 (might be too tall).

 

[nevrenufhp]

If you're looking for some better power, check in to a Mechanical DT466. Ideally a 95-97. They are happy to spin higher than a 3116, plus you can make double the 3116's power pretty easily(turbo, pump, and injectors). Then, the problem becomes busted driveline parts. I would mention a Cummins 8.3, but they are likely a bit too tall. If you dont plan on towing anything, a Cummins 5.9 may do it ok, but will still be working hard.

 

[Johno176]

I agree with scottmandu, the C7 would be a great re-fit because it would drop right in with only minor mods to electrical/computer. The C7 can be reprogrammed to 370 hp by cat dealer.

 

[deshet]

If you're looking for some better power, check in to a Mechanical DT466. Ideally a 95-97. They are happy to spin higher than a 3116, plus you can make double the 3116's power pretty easily(turbo, pump, and injectors). Then, the problem becomes busted driveline parts. I would mention a Cummins 8.3, but they are likely a bit too tall. If you dont plan on towing anything, a Cummins 5.9 may do it ok, but will still be working hard.

Does anyone know if the DT466e will fit. I have acess to a few of these, mostly 1998-2002

Thanks

 

[Awesomeness]

I cracked my block, because of the aforementioned driveline vibration. I swapped the engine myself too (just another 3116). The swap is straightforward, and completely documented in the manual, but took like 40 hours of work. You can get engines out of other scrapped FMTVs.

 

[deshet]

I cracked my block, because of the aforementioned driveline vibration. I swapped the engine myself too (just another 3116). The swap is straightforward, and completely documented in the manual, but took like 40 hours of work. You can get engines out of other scrapped FMTVs.

How many miles did you have on your truck when it happened? I am only at 2000 miles but I need to make sure that everything is good to go.
It is crazy that a driveline vibration can crack a block.

Thanks

 

[Awesomeness]

How many miles did you have on your truck when it happened? I am only at 2000 miles but I need to make sure that everything is good to go.
It is crazy that a driveline vibration can crack a block.

There were about 23k miles on mine, but age can be a factor too (e.g. seals fail, rust in the bearings wears them faster, etc.).

You should read the military's driveline studies. Shortly after the trucks came out, they were having issues with driveline vibrations ripping the back off the transmission, and other crazy stuff. The studies recommended that the Army change to a better driveshaft design, but instead they went with a workaround solution of just putting on stronger shafts and u-joints (which ALL trucks received).

We've seen this kind of failure on a number of members' trucks, including mine. (It's all documented in my troubleshooting guide, in my signature.) Considering how completely it can ruin your day, even if the percentage of trucks that experience the problem are small, I think it's worth a couple hundred bucks to make sure you don't get much more costly and time consuming repairs.

 

[coachgeo]

I agree with scottmandu, the C7 would be a great re-fit because it would drop right in with only minor mods to electrical/computer. ...

I've seen this said...... but have seen OPPOSITE* said so not sure the truth on this.

* see post 24 - 26

( https://www.steelsoldiers.com/showt...mixing-guide&p=2141283&viewfull=1#post2141283 )